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While driving along a snow-covered rural road, admiring Minnesota’s winter landscape, you catch a glimpse of something bright in the distance. It’s a person standing on a frozen river dressed in vibrant lime green reflective gear. "Uffda," you’d say. "What could they possibly be doing?"
If this sounds familiar, there’s a good chance you’ve witnessed a USGS Hydrologic Technician in action, making an ice discharge measurement. For most Minnesotan’s, venturing onto river ice is a one-way ticket to Valhalla, but for the intrepid streamgager, navigating river ice is routine work! "Why are they out there, you might say?" Well, because the USGS calculates streamflow year around, even when the river is frozen over.
In Minnesota, ice typically sets in around late November, a celebrated time known to many mid-westerners as “Ice-In”.
Ice discharge measurements play a crucial role in estimating the winter portion of annual hydrographs. Each year as rivers begin to freeze over, backwater becomes the rule, not the exception. This backwater affect refers to the fluctuations in gage height caused by the formation and release of channel ice. During these periods, the typical stage-discharge relations used to calculate discharge become unreliable.
Much like summer open water wading measurements, Winter ice measurements utilize similar methods for measuring area and velocity used in the computation of stream flow. The key difference lies in the need to drill through the ice to measure the flowing water beneath. A minor inconvenience, but well worth the effort.
Ice measurements can be safe and successful with the right approach. The trick is knowing when to walk away from a dangerous situation. Even the most seasoned streamgager can be fooled by the capricious nature of river ice. To avoid risk, the USGS streamgager is equipped to test the ice ahead of each step. This precaution helps avoid the perils of treading on thin ice. For a streamgager, a sturdy chisel in hand and some good common sense is your best friend.
As the seasons shift from summer to winter, USGS streamgagers begin their preparations for making annual ice measurements. They bring out their sleds, sharpen their chisels, fuel their ice augers, and dust off those lime green float coats that can be seen by distant passerby’s.
You might ask, “is there really a difference between an ice measurement and a summer wading measurement?” And the streamgager might reply, with a hint of mirth " the proof is in the footing!"
Hydrologic technician Garret Welsh conducts an Ice Rod measurement through an augered hole in the frozen St. Croix river near streamgage 05341550 in Stillwater, Minnesota. An Ice Rod is a heavy-duty, 1-inch (2.5 centimeter) diameter, lightweight aluminum rod used for suspending ice meters in fast velocities.
USGS Upper Midwest Water Science Center staff, Supervisory Hydrologic Technician Russ Buesing and Hydrologic Technician Josh Larson pose for the streamgage webcam while making an under-ice discharge measurement at the Knife River near Two Harbors, MN.
USGS Upper Midwest Water Science Center staff, Supervisory Hydrologic Technician Russ Buesing and Hydrologic Technician Josh Larson pose for the streamgage webcam while making an under-ice discharge measurement at the Knife River near Two Harbors, MN.
Pecatonica River at Martintown, Wisconsin streamgage in winter.
https://waterdata.usgs.gov/monitoring-location/05434500/
The path cleared of snow on the river contains drilled holes that are used to measure streamflow under the ice.
Pecatonica River at Martintown, Wisconsin streamgage in winter.
https://waterdata.usgs.gov/monitoring-location/05434500/
The path cleared of snow on the river contains drilled holes that are used to measure streamflow under the ice.
Hydrologic technician Brendan Hallmark uses an ice auger to drill a hole in the frozen Pecatonica River at the Martintown, Wisconsin streamgage in winter.
Hydrologic technician Brendan Hallmark uses an ice auger to drill a hole in the frozen Pecatonica River at the Martintown, Wisconsin streamgage in winter.
Hydrologic technician Brendan Hallmark drills a hole in the frozen Pecatonica River at the Martintown, Wisconsin streamgage in winter.
Hydrologic technician Brendan Hallmark drills a hole in the frozen Pecatonica River at the Martintown, Wisconsin streamgage in winter.
Scientist holding cell phone reflected in water in hole drilled in the frozen Pecatonica River, Wisconsin.
Scientist holding cell phone reflected in water in hole drilled in the frozen Pecatonica River, Wisconsin.
Hydrologic technician Garret Welsh carries a large ice auger while walking across the frozen St. Croix river near streamgage 05341550 in Stillwater, Minnesota.
Hydrologic technician Garret Welsh carries a large ice auger while walking across the frozen St. Croix river near streamgage 05341550 in Stillwater, Minnesota.
Hydrologic technician Garret Welsh conducts an Ice Rod measurement through an augered hole in the frozen St. Croix river near streamgage 05341550 in Stillwater, Minnesota. An Ice Rod is a heavy-duty, 1-inch (2.5 centimeter) diameter, lightweight aluminum rod used for suspending ice meters in fast velocities.
Hydrologic technician Garret Welsh conducts an Ice Rod measurement through an augered hole in the frozen St. Croix river near streamgage 05341550 in Stillwater, Minnesota. An Ice Rod is a heavy-duty, 1-inch (2.5 centimeter) diameter, lightweight aluminum rod used for suspending ice meters in fast velocities.
USGS hydrologic technician Dan Daly takes a discharge measurement (the amount of water passing a location) of the Minnesota River near streamgage 05292000, Minnesota River at Ortonville, MN.
USGS hydrologic technician Dan Daly takes a discharge measurement (the amount of water passing a location) of the Minnesota River near streamgage 05292000, Minnesota River at Ortonville, MN.
Scientist conducting measurement through hole drilled in ice covered surface of the Minnesota River in western Minnesota.
Scientist conducting measurement through hole drilled in ice covered surface of the Minnesota River in western Minnesota.
Two scientists stand on the frozen Minnesota River covered in snow conducting fieldwork in western Minnesota.
Two scientists stand on the frozen Minnesota River covered in snow conducting fieldwork in western Minnesota.
Field office chief Dan Daly smiles for the camera with frost-covered eyelashes while conducting fieldwork on a frigid winter day in Minnesota.
Field office chief Dan Daly smiles for the camera with frost-covered eyelashes while conducting fieldwork on a frigid winter day in Minnesota.
Field office chief Dan Daly takes a streamflow measurement through a hole drilled in the frozen Minnesota River in western Minnesota.
Field office chief Dan Daly takes a streamflow measurement through a hole drilled in the frozen Minnesota River in western Minnesota.
Field office chief Dan Daly and a student hydrologist pull a sled containing water sampling equipment on the frozen Minnesota River in western Minnesota.
Field office chief Dan Daly and a student hydrologist pull a sled containing water sampling equipment on the frozen Minnesota River in western Minnesota.
Hydrologic technician Scott Adolphson conducts a streamflow measurement through a hole in a frozen river in western Minnesota, while an ice auger rests in a hole in the ice in the foreground.
Hydrologic technician Scott Adolphson conducts a streamflow measurement through a hole in a frozen river in western Minnesota, while an ice auger rests in a hole in the ice in the foreground.
Hydrologic technician Scott Adolphson takes a stream discharge measurement through a hole in ice while kneeling on a frozen river in western Minnesota.
Hydrologic technician Scott Adolphson takes a stream discharge measurement through a hole in ice while kneeling on a frozen river in western Minnesota.
Hydrologic technician Brett Savage conducts an ice discharge measurement on the Minnesota River in Montevideo, Minnesota.
Hydrologic technician Brett Savage conducts an ice discharge measurement on the Minnesota River in Montevideo, Minnesota.
Hydrologic technician Garret Welsh conducts an Ice Rod measurement through an augered hole in the frozen St. Croix river near streamgage 05341550 in Stillwater, Minnesota. An Ice Rod is a heavy-duty, 1-inch (2.5 centimeter) diameter, lightweight aluminum rod used for suspending ice meters in fast velocities.
USGS Upper Midwest Water Science Center staff, Supervisory Hydrologic Technician Russ Buesing and Hydrologic Technician Josh Larson pose for the streamgage webcam while making an under-ice discharge measurement at the Knife River near Two Harbors, MN.
USGS Upper Midwest Water Science Center staff, Supervisory Hydrologic Technician Russ Buesing and Hydrologic Technician Josh Larson pose for the streamgage webcam while making an under-ice discharge measurement at the Knife River near Two Harbors, MN.
Pecatonica River at Martintown, Wisconsin streamgage in winter.
https://waterdata.usgs.gov/monitoring-location/05434500/
The path cleared of snow on the river contains drilled holes that are used to measure streamflow under the ice.
Pecatonica River at Martintown, Wisconsin streamgage in winter.
https://waterdata.usgs.gov/monitoring-location/05434500/
The path cleared of snow on the river contains drilled holes that are used to measure streamflow under the ice.
Hydrologic technician Brendan Hallmark uses an ice auger to drill a hole in the frozen Pecatonica River at the Martintown, Wisconsin streamgage in winter.
Hydrologic technician Brendan Hallmark uses an ice auger to drill a hole in the frozen Pecatonica River at the Martintown, Wisconsin streamgage in winter.
Hydrologic technician Brendan Hallmark drills a hole in the frozen Pecatonica River at the Martintown, Wisconsin streamgage in winter.
Hydrologic technician Brendan Hallmark drills a hole in the frozen Pecatonica River at the Martintown, Wisconsin streamgage in winter.
Scientist holding cell phone reflected in water in hole drilled in the frozen Pecatonica River, Wisconsin.
Scientist holding cell phone reflected in water in hole drilled in the frozen Pecatonica River, Wisconsin.
Hydrologic technician Garret Welsh carries a large ice auger while walking across the frozen St. Croix river near streamgage 05341550 in Stillwater, Minnesota.
Hydrologic technician Garret Welsh carries a large ice auger while walking across the frozen St. Croix river near streamgage 05341550 in Stillwater, Minnesota.
Hydrologic technician Garret Welsh conducts an Ice Rod measurement through an augered hole in the frozen St. Croix river near streamgage 05341550 in Stillwater, Minnesota. An Ice Rod is a heavy-duty, 1-inch (2.5 centimeter) diameter, lightweight aluminum rod used for suspending ice meters in fast velocities.
Hydrologic technician Garret Welsh conducts an Ice Rod measurement through an augered hole in the frozen St. Croix river near streamgage 05341550 in Stillwater, Minnesota. An Ice Rod is a heavy-duty, 1-inch (2.5 centimeter) diameter, lightweight aluminum rod used for suspending ice meters in fast velocities.
USGS hydrologic technician Dan Daly takes a discharge measurement (the amount of water passing a location) of the Minnesota River near streamgage 05292000, Minnesota River at Ortonville, MN.
USGS hydrologic technician Dan Daly takes a discharge measurement (the amount of water passing a location) of the Minnesota River near streamgage 05292000, Minnesota River at Ortonville, MN.
Scientist conducting measurement through hole drilled in ice covered surface of the Minnesota River in western Minnesota.
Scientist conducting measurement through hole drilled in ice covered surface of the Minnesota River in western Minnesota.
Two scientists stand on the frozen Minnesota River covered in snow conducting fieldwork in western Minnesota.
Two scientists stand on the frozen Minnesota River covered in snow conducting fieldwork in western Minnesota.
Field office chief Dan Daly smiles for the camera with frost-covered eyelashes while conducting fieldwork on a frigid winter day in Minnesota.
Field office chief Dan Daly smiles for the camera with frost-covered eyelashes while conducting fieldwork on a frigid winter day in Minnesota.
Field office chief Dan Daly takes a streamflow measurement through a hole drilled in the frozen Minnesota River in western Minnesota.
Field office chief Dan Daly takes a streamflow measurement through a hole drilled in the frozen Minnesota River in western Minnesota.
Field office chief Dan Daly and a student hydrologist pull a sled containing water sampling equipment on the frozen Minnesota River in western Minnesota.
Field office chief Dan Daly and a student hydrologist pull a sled containing water sampling equipment on the frozen Minnesota River in western Minnesota.
Hydrologic technician Scott Adolphson conducts a streamflow measurement through a hole in a frozen river in western Minnesota, while an ice auger rests in a hole in the ice in the foreground.
Hydrologic technician Scott Adolphson conducts a streamflow measurement through a hole in a frozen river in western Minnesota, while an ice auger rests in a hole in the ice in the foreground.
Hydrologic technician Scott Adolphson takes a stream discharge measurement through a hole in ice while kneeling on a frozen river in western Minnesota.
Hydrologic technician Scott Adolphson takes a stream discharge measurement through a hole in ice while kneeling on a frozen river in western Minnesota.
Hydrologic technician Brett Savage conducts an ice discharge measurement on the Minnesota River in Montevideo, Minnesota.
Hydrologic technician Brett Savage conducts an ice discharge measurement on the Minnesota River in Montevideo, Minnesota.
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